Methods for dechlorination disposal of polyvinyl chloride wastes and apparatus thereof

Abstract: The present invention provides methods for making gases generated in the treatment of polyvinyl chloride wastes harmless by neutralization and dissolving, and an apparatus thereof, and a suction-type solution filter container to be used, and providing to shape useful materials or components, such as activated carbon with excellent adsorbability, from the post-treated residues of the wastes. Polyvinyl chloride wastes are put in the sealed container 1 and heated at 400°C or less without oxygen or with air-blocked condition; the gases from the wastes, such as chlorine or hydrogen chloride, are sucked to extract from the container; the extracted gases are introduced into the suction-type solution filter container with liquid filtration agents to pass therethrough; chlorine is removed and reduced in volume from the wastes in the sealed container.

Description: Field of the Invention This invention relates to methods for making noxious gases harmless and odorless after neutralization or dissolving and to an apparatus thereof, when the gases are generated in the disposal of wastes, such as polyvinyl chloride films and sheets; and this invention relates to a suction-type solution filter container used thereby, and methods for forming carbon materials, such as an activated carbon with excellent absorbability from the residue after heat-treating the disposal as described, or for salvaging the disposal as a tar component, or methods for forming civil engineering and building materials after drying and setting the tar component, without leaving any disposal residues. Background of the Invention Polyvinyl chloride films applied to agricultural or horicultural vinyl houses are used for a fixed period, and then replaced with a new one because of the deterioration of optical transmission or serviceability with age or by dust adhesion. As a result, used polyvinyl chloride films arise, and it is necessary to dispose of them with a certain method. If the used films are heat-treated with an ordinary refuse incinerator under the air (oxygen) atmosphere, the incineration temperature rises higher with the generation of noxious gases, such as a hydrogen chloride gas and dioxins (popularly known as chlorodibenzoxines), and of a malodor, so that the refuse incinerator will be damaged, or polution will be caused. Therefore, the heat treatment is seldomly practiced. Further methods include a method for extracting the oils from polyvinyl chloride to be salvaged, or of throwing the used films into reclaimed land without any treatment; the former, however, causes problems with salvage costs and efficiency, the latter makes the land loose and destroys the natural circulation system; therefore, these are not excellent methods. Thus, it is suggested that the waste plastic materials including chloric polymer compounds, such as polyvinyl chloride, should be treated making generated gases, such as hydrogen chloride gases, harmless. In Japanese Provisional Publication No. 3040 of 1988, for example, a fusing-setting method was provided for heating and fusing waste plastic materials at pyrolysis temperature of at least 150 °C or more with crushing and kneading, while calcium salts were introducted, so that the harmful hydrogen chloride gases generated would be rendered harmless by the salts. This method conducted under the air atmosphere (oxygen), however, has a potential for generating harmful materials to the human body and a danger of ignition. Moreover, this method needs to dispose of the solid waste plastic materials. Summary of the Invention The present invention provides methods for rendering harmless the gases generated in the treatment of polyvinyl chloride wastes, and an apparatus thereof, providing a suction-type solution filter container used thereby, and creating useful substances or materials, such as activated carbon from the residues after heating of the waste, as described, with excellent adsorbability, in the light of the waste disposal of polyvinyl chloride generating harmful hydrogen chloride gases under present condition in the conventional arts. In order to overcome the object as described, the present invention provides a disposal method, mainly comprising: putting polyvinyl chloride wastes into a sealed container to evacuate oxygen or stop the air therein to heat the wastes at 400 °C or less; absorbing and extracting gases generated from the wastes by the heat, such as chlorine and hydrogen chloride, from the container; introducing the extracted gases into the suction-type solution filter container including liquid filtration agents to passe the gases through the agents: thus achieving a removal and a reduction in volume of the chlorine from the wastes in the sealed container. In order to carry out the methods as described, the present invention provides an apparatus, mainly comprising: a sealed heat container capable of including polyvinyl wastes and of heating the wastes to a required temperature under oxygen evacuation or air-exclusion conditions; a suction-type solution filter container which includes liquid filtration agents leaving space to an upper side, applying absorptivity to gases collecting the upper side space after treatments, such as dissolution and neutralization, through the filtration agents, wherein an end of a gas introduction pipe is connected to the sealed heat container and located in the filtration agent; and a suction fan device provided by continous connection through the upper space of the solution filter container. The methods of the present invention can neutralize or dissolve noxious gases generated in the treatment of polyvinyl chloride wastes, such as chlorine and hydrogen chloride, in the suction-type solution filter container, to achieve harmlessness and odorlessness; and the methods can change the post-heating residues of the wastes into useful materials with excellent adsorbability, for example, after re-heating disposal at higher temperature. Brief Summary of the Invention Figure 1 illustrates a front view in section of an apparatus as an embodiment of the harmless disposal methods for polyvinyl chloride wastes according to the present invention. Detailed Description of the Preferred Embodiments Now, embodiments of the present invention will be described, refering to Fig. 1. Figure 1 illustrates a front view in section of an apparatus as an embodiment of the harmless disposal methods for polyvinyl chloride wastes according to the present invention. In Fig. 1, the numeral 1 shows a sealed containder for including polyvinyl wastes inside to heat; the numeral 2 shows an outer container of the sealed container 1; and the numeral 3 shows an inner container thereof. The outer container 2 is sealed with the inner container 3 in insulation. The inner container 3 contains polyvinyl chloride wastes 4 (sometimes called "disposal objects", hereunder) evacuating the gases in the surplus space to the outside to remove oxygen from the inside of the inner container 3. The inner container 3 also blocks the interchange with the outer air. The numeral 5 shows a heat means set on the lower side of the inner container. The heat means 5 heats the inner container 3 at less than 400 °C, preferably at 350 °C or less, to pyrolytically decompose polyvinyl chloride wastes 4 by heating and fusing. The heat means 5 is an electrical heater herein; however, exhaust heat means for combustion treatment of wastes also may be used; alternatively, a heat means by far inrared rays and an electrical heater or any electromagnetic wave means, such as high-frequency induction heater and magnetrons, or an optional combination of these means may be used. The numeral 6 shows a first temperature sensor. The numeral 7 shows a second temperature sensor. The numeral 8 shows a third temperature sensor. Each sensor detects the internal temperature of the inner container 3, respectively at the backmost, the center or the front points of the container 3 along the depth. The temperature in the inner container 3 ranges from about 150-240 °C to temperatures of about 350 °C up to temperatures under 400 °C, and the heat temperature is directed to change step by step according to a time schedule in respect of the gases to be generated from disposal objects 4. Further, the inside pressure of the inner container 3 is reduced by the absorptive action from the side 11, 12, 13 of a suction-type filter solution container as described hereunder; polyvinyl chloride wastes 4 actually can be pyrolytically decomposed at lower temperatures than the temperatures described. The lower side temperature alsong the depth of the inner container 3 is higher than the upper, but there is a little difference between the upper and lower sides, because polyvinyl chloride wastes 4 convect by heating and fusing. The numeral 9 is a gas introduction pipe to connect to the upper side of the inner container 3 in the sealed container 1 for introducing the gas generated in the inner container 3 to the outside of the sealed container 1. The numeral 10 is a connecting pipe connected to the introduction pipe 9 to introduce the generated gases to the other suction-type solution filter containers 11, 12, 13. The numeral 11 shows a first suction-type filter solution container including a liquid filtration agent therein; the numeral 12 shows a second suction-type filter solution container including a liquid filtration agent therein; and the numeral 13 shows a third suction-type filter solution container including a liquid filtration agent therein, and a suction device 14 is attached on the upper cover component. In reference to the apparatus shown in Fig. 1, the first suction-type filter solution container 11 is connected to the inner container 3 through the introduction pipe 9 and the connecting pipe 10, and connected to the second suction-type solution filter 12 through the connecting pipe 15. Moreover, the second suction-type solution filter is connected to the third suction-type solution filter container 13 through the connecting pipe 16. Although the first, second and third suction-type filter solution containers 11, 12, 13 are serially connected to the inner container 3 in this order, these three containers 11, 12, 13 may be parallelly connected to the inner container 3. In the case of a parallel connection, a suction device 14 described hereunder is attached to cover components 11a, 12a, 13a on the upper side of the suction-type solution filter containers 11, 12, 13; however, a larger suction device 14 may be designed to suck the gases in each container simultaneously. Thus, the front end side of the connecting pipe 10 is hermetically penetrated into the hole formed about the center plane of the upper cover component 11a of the first suction-type filter solution, while the rear end is immersed in filtration agents S in the filter container 11 and connectively fixed to be located a little higher from the bottom of the container 11. The rear end side of the connecting pipe 15 is hermetically penetrated into a hole formed in the upper cover component 11a of the first suction-type filter solution container 11, and the rear end is arranged to be located in the upper space of the filter container 11; the front end side of the connecting pipe 15 is penetrated into a hole about the center plane of the upper cover component 12a of the second suction-type filter solution container 12, while the front end is immersed in filtration agents S in the filter container 12, and connectively fixed to be located a little higher from the bottom of the container 12. Furthermore, the connecting pipe 16 is connected in the way described for connecting pipe 15, between the second and third suction-type filter solution containers 12, 13. About 3 quarters of filtration agents S are respectively contained in the first, second and third suction-type filter solution containers, and a surplus space is kept in the upper part of each container. As filtration agents S, the following solutions may be used: water (H 2 O); surface-active aqueous solution including soap, sodium alkyl benzensulfonic acid, or the like; alkaline solutions including caustic soda (NaOH), caustic potash (KOH), calcium hydroxide (Ca(OH 2 )), or the like; or oily solutions, such as gas oil, kerosine and turpenine oil. However, caustic soda is used herein. Alternatively, for example, aqueous solutions may be contained in the first, second and third suction-type filter solution containers 11, 12, 13; or aqueous solution may be contained in the first and second suction-type filter solution containers 11, 12, while caustic soda is contained in the third suction-type filter solution container 13. Each vapor-liquid mixing plate is attached to the front end side of each connecting pipe 10, 15, 16 located in filtration agents S respectively contained in each suction-type filter solution container 11, 12, 13 to be connected so that the gases introduced from each front end to each filtration agent may sufficiently cause catalytic reaction to each filtration agent S. These vapor-liquid mixing plates 17, 18, 19 are provided with plural small permeable holes in a plate component with acid and alkaline resistivities; alternatively a filter with fine meshes may be used. Further, many small permeable holes iwth about 0.5 mm diameter may be provided with peripheral walls of the front end of the connecting pipe 10, 15, 16 after sealing thereof. Thus, the gases introduced from the front end of each connecting pipe 10, 15, 16 form bubbles, so that the catalytic reaction with filtration agents S can be promoted together with the effect of the vapor-liquid mixed plates 17, 18, 19. Two or more vapor-liquid mixed plates 17, 18, 19 may be respectively arranged on the front side of each connecting pipe 10, 15, 16, keeping appropriate intervals to render multi-stages. It is possible to turn the vapor-liquid mixed plates 17, 18, 19, at the side of the front end to promote catalytic reaction of the gases with filtration agents S. If the vapor-liquid mixing plates 17, 18, 19 are directed to turn, the front side of each connecting pipe 10, 15, 16 will be connected to the lower peripheral sides of each first, second and third suction-type filter solution container 11, 12, 13, or connected about the center of the bottom components, because the motors for turning vapor-liquid mixing motor must be attached about the plane center of each upper cover component 11a, 12a, 13a of each suction-type filter solution container 11, 12, 13. If the vapor-liquid mixing plates 17, 18, 19 are desired to turn, downward skirt 17a-19a may be sometimes formed on the periphery of each vapor-liquid mixed plate 17, 18, 19. In each suction-type filter solution container 11, 12, 13, hydrogen chloride (HCl) gas mainly reacts with caustic soda (NaOH) to generate NaCl and H 2 O. If noxious hydrogen chloride gas is not completely neutralized in the first suction-type filter solution container 11, the non-neutral gas will be neutralized in the second suction-type filter solution container 12, and if noxious hydrogen chloride gas is not completely neutralized in the second suction-type filter solution container 12, the non-neutral gas will be neutralized in the third suction-type filter solution container 13; the noxious hydrogen chloride gas, therefore, can be almost completely neutralized to be harmless. The number and volume of the suction-type filter solution containers 11, 12, 13 for serial connection is determined according to the size of the inner container 3 in the sealed container 1. If suction-type filter solution containers 11, 12, 13 are used one by one, a container with a certain large volume is used for the filter container. Filtration agents S in each suction-type filter solution container 11, 12, 13 should be replaced with a new alkaline solution after every treatment. When an aqueous solution is used as filtration agent, the solution with noxious gases, such as chlorine and hydrogen chloride gases, is treated by neutralization or the like with another apparatus for harmlessness. If plural suction-type filter solution containers 11, 12, 13 are parallelly connected to the sealed container 1, after different filtration agents S are contained in each suction-type filter solution container 11, 12, 13, and after heat temperature by the heat means 5 is adjusted, for example, while the generated gases are extracted step by step keeping appropriate periods, the generated gases can be introduced to the different suction-type filter solution container 11, 12, 13 by a switch valve according to the kinds of the generated gas. For example, sulfur dioxide (SO 2 ) introduces the generated gases into the suction-type filter solution container including calcium hydroxide (Ca(OH 2 ) solution; hydrogen chloride gas introduces the generated gases into the suction-type filter solution container including an aqueous or caustic soda solution; and chlorine gas introduces the generated gases into the suction-type filter solution container including calcium hydroxide (Ca(OH 2 )) or aqueous solution. Moreover, an alkaline solution and water can be enclosed with polyvinyl wastes 4 in the inner container 3 in the sealed container 1 in advance, as well as the serial or parallel suction-type filter solution container 11, 12, 13 as described. In this case, polyvinyl chloride wastes 4 are heated, fused and pyrolytically decomposed, while the gases, such as chlorine and hydrogen chloride, are neutralized; less noxious gases can be generated; the noxious gases can be harmless with the effect of suction-type filter solution containers 11, 12, 13. Black residues are left in the inner container 3 in the sealed container 1 after the heat-treating of polyvinyl chloride wastes 4. The residues are presumed to be insoluble polymer materials generated as follows: After a side chain of polyvinyl chloride is dropped out, and after the polyvinyl chloride has a polyene structure, these polyene structures crosslink each other or cause cyclarization. The residues of insoluble polymer materials has been rendered almost completely harmless by the chloride removal method of the present invention; the residues have no potential to destroy the environment, even if thrown into land as they are. However, the present invention provides an improved disposal method for reheating these insoluble polymer materials with addition of steam at 700-800 °C; in this method, we could confirm that activated carbon, which shows extreme adsorbability, can be obtained after the polymer materials are activated. In fact, 300 g of vinyl chloride sheet was tested for the content of chloride which is included in the black residues left after the treatment by the method according to the present invention; the content was 152 mg. The test was carried out with nitric acid extraction and silver nitrate titration (C1 conversion) at Enviroment Management Center Inc. 300 g vinyl chloride sheet includes 30 % weight of plasticized agents and 70 % weight (210 g) of polyvinyl chloride with 60 % (126 g) of chlorine; however, the C1 quantity of the black residues treated by the present methods was 125 mg by weight, and it can be said the obtained residues are almost completely harmless. Therefore, the black residues left after the treatment of polyvinyl chloride according to the present invention includes little chlorine; for example, black coal can be obtained after combustion of the black residues under oxygen or the air, as post-treatment. Further the black residues left in the inner container 3 in the sealed container 1 may be reheated at 400-500 °C, whereby the tar (or oil) component is vaporized to pass the suction-type filter solution container 11 to be salvaged in a safe or harmless manner. The salvaging of the tar (or oil) component may be directly carried out, after the sealed container 1 is reheated followed by temperature drop to extract the tar (or oil) component therein. Moreover, solid materials with optional formation for civil engineering or for construction can be shaped by heating, softening and molding the black residues left after the process of the present invention, or by heating and molding the tar (or oil) component salvaged. As described hereabove, when caustic soda solution is used for filtration agents S, the noxious gases generated from polyvinyl chloride wastes treated in the sealed container 1, such as chlorine or hydrogen chloride gas, can be almost completely rendered harmless, according to the present invention. When an aqueous solution is used as filtration agent S, though dependent on the temperature of the solution, noxious gases, such as chlorine and hydrogen chloride, can, in a considerable amount, be dissolved into the solution at ordinary temperature. As described hereabove, in the present invention, noxious hydrogen chloride gases from polyvinyl chloride wastes can be passed through the liquid filtration agents in the suction-type filter solution container to dissolve and neutralize with deodorizing for treatment rendering the end-products harmless. Further, as the wastes can be heated, fused and pyrolitically decomposed at 400 °C or less, preferably at 350 °C or less, blocking the air in the sealed oven (without oxygen), no noxious materials, such as dioxine which represents oxygen-including aromatic chloride, will be generated. Moreover, according to the present invention, while the used polyvinyl chloride enables the removal of chlorine, deodorizing and volume reduction, the black residues presumed as insoluble polymer materials left in the sealed oven present no problem when reheated or burned, because the residues are almost completely harmless; on the contrary, black coal and activated carbon or molded materials thereof can be obtained. Furthermore, the residues can be disposed of, for example thrown into land without any problems.

Claims: A method for removing chlorine from polyvinyl chloride wastes, comprising the steps of putting polyvinyl chloride wastes (4) into a sealed container (3) to heat at 400° C or less under exclusion of air or oxygen, extracting chlorine and hydrogen chloride gases, from the wastes (4) by heating, and introducing the extracted gases into a suction-type filter solution container (11, 12, 13) containing liquid filtration agents, thus achieving a removal and a reduction in volume of the chlorine from the wastes (4) in the sealed container (3). A method according to claim 1, wherein alkaline solution and water are enclosed with the wastes (4) in the container (3) and heated together with the wastes (4). A method according to claim 1 or 2, wherein the heating of the sealed container (3) is achieved by at least one of the following means: an electric heater, an electric heater with far infrared rays, an oil combustion means, an electromagnetic heating means, a high-frequency induction heating means and exhaust heating means driven by a combustion treatment of wastes. A method according to one of the claims 1 to 3, wherein a waste material (4) from which chlorine has been removed and reduced in volume according to the method of claim 1 is exposed to steam at about 700 to 800° C, whereby it is transformed into activated carbon. A method according to one of the claims 1 to 3, wherein a waste material (4), from which chlorine has been removed and reduced in volume according to the method of claim 1 is changed into carbon (black coal) by burning with oxygen or air. A method according to claim 1, wherein the material, from which the chlorine has been removed is heated at 400 to 500° C in the sealed container (3) or another container, a tar component of the material is vaporized, the vapored tar component is passed through a suction-type solution filter material, or the temperature of the container is lowered, and then the tar component is salvaged as oil. A method according to any one of the claims 1 to 6, wherein two or more suction type solution filter containers (11, 12, 13) are serially connected for passing the gases extracted from the sealed container (3) serially through filtration agents S in each container (11, 12, 13). A method according to any one of the claims 1 to 6, wherein two or more suction type solution filter containers (11, 12, 13) are connected in parallel for passing the gases generated in the sealed container (3) in parallel through filtration agents S in each container (11, 12, 13). A method according to claim 8, wherein each container (11, 12, 13) contains a different filtration agent S, and switching means are provided, by means of which gases generated in the sealed container (3) can be selectively introduced into respective containers (11, 12, 13), especially in accordance with the generation in the sealed container (3) of different gases at various temperatures. A method according to any one of the claims 1 to 9, wherein the filtration agents S contained in the suction-type filter solution containers are water, surface-active aqueous solutions, alcohol, alkaline solutions or oily solutions. An apparatus for treating hydrogen chloride wastes, especially in connection with the removal of chloride from polyvinyl chloride wastes, comprising: a sealed heating container (3) for containing hydrogen-chloride wastes produced during the heating of corresponding waste materials (4), especially polyvinyl chloride wastes, at least one suction-type filter solution container (11, 12, 13) comprising a container body, the volume of which is partly filled with a liquid filtration agent S in such a way that a surplus space remains at the upper side of the container, a pipe (10, 15, 16) introducing gases produced in the container (3) into the filtration agent S, the inlet of which is arranged in the container (3), the outlet of which is submerged underneath the fluid level of the liquid filtration agent S, and a suction-device (14), the suction inlet of which is arranged in the surplus space above the liquid filtration agent S, and wherein at least one vapor-liquid mixing plate (17, 18, 19) with gas-permeable holes is attached to the container (11, 12, 13) in such a way as to be immersed within the filtration agent in the container (11, 12, 13) and means for selectively heating the wastes to a predetermined temperature between 150° C and 350° C under oxygen- or air-exclusion conditions. An apparatus according to claim 11, wherein the vapor-liquid mixing plate (17, 18, 19) is rotatably moveable about an axis defined by the outlet ends of the connecting pipes (10, 15, 16). An apparatus according to any one of claims 11 to 12, wherein the outlet end of the gas introduction pipe (10) is arranged in the serially first suction-type solution container (11), which is serially connected to one or more containers (12, 13), while the suction device (14) communicates with the surplus space in the serially last suction-type solution filter container (13). An apparatus according to any one of claims 11 to 13, wherein two or more suction-type filter containers (11, 12, 13) are serially connected, and the gases generated in the sealed heating container (3) are introduced into the serially first filter container (11) below the surface of the liquid filtration agent, the gas reaching the surface of the liquid filtration agent in the serially first filter container (11) being introduced into one or more serially connected filter container (12, 13) underneath the surface of the respective liquid filtration agent.

Inventors: MOTADA KENRO, MOTADA, KENRO, MOTADA, KENRO, C/O MOTODA ELECTRONICS CO., LTD.
Applicants: MOTODA ELECTRONICS, MOTODA ELECTRONICS CO., LTD.
Application year: 1994
Main classification: A62D3
IPC codes: B29B17, C10B53, B01D53, B09B3, C01B31, C08J11, A62D101